DESCRIPTION: (adapted from Abstract) The investigator advances the hypothesis that because octopus cells of the cochlear nuclei detect synchronous firing of groups of auditory nerve fibers, that they may mediate natural sound detection. The proposed studies will investigate the nature and modulation of the conductances that have been identified in the octopus cells to learn how gain of coincidence detection is regulated. The four specific aims are as follows: 1 Test whether the inwardly rectifying conductance of octopus cells is modulated through second messenger systems. 2 Determine whether the surgical and genetic removal of auditory nerve input affects the excitability of octopus cells. 3 Describe the potassium and inwardly rectifying conductances with whole-cell voltage clamping. 4 Test the hypothesis that the tonotopic arrangement of inputs on the dendrites of octopus cells compensates for the traveling wave delay in the cochlea and enhances coincidence detection.